The present invention relates to a method of making MOS transistors, and particularly to such a method which does not adversely affect the radiation resistance of the transistor.
For many uses of MOS transistors it is desirable that the transistor be relatively resistant to dosages of radiation, i.e., the electrical characteristics of the transistor are not adversely affected when the transistor is subjected to radiation. We have discovered that the radiation resistance of an MOS transistor is not only a function of the materials used to make the transistor but is also a function of how it is fabricated. We have found that any processing step which requires treating the transistor at a high temperature, i.e., above about 900.degree. C., after the channel oxide layer has been formed, results in a degradation of the radiation resistance of the transistor. We believe that such heating of the transistor removes the charges formed in the channel oxide layer which in turn results in poor radiation resistance.